1. Field of the Invention
The invention relates to the use of a micellar solution of a thin film spreading agent comprising an acylated polyether polyol in the breaking or prevention of petroleum emulsions. More specifically, the invention relates to a composition in which water replaces all or a substantial part of the organic solvents formerly required for preparation of liquid solutions of this interfacially active compound.
2. Description of the Prior Art
One of the principal uses of the present composition is in the breaking of petroleum emulsions to permit the separation thereof into two bulk phases. Much of the crude petroleum oil produced throughout the world is accompanied by some water or brine which originates in or adjacent to the geological formation from which the oil is produced. The amount of aqueous phase accompanying the oil may vary from a trace to a very large percentage of the total fluid produced. Due to the natural occurrence in most petroleum of oil-soluble or dispersible emulsifying agents, much of the aqueous phase produced with oil is emulsified therein, forming stable water-in-oil emulsions.
The literature contains numerous references to such emulsions, the problems resulting from their occurrence, and the methods employed to break them and separate salable petroleum. See, for example, "The Technology of Resolving Petroleum Emulsions" by L. T. Monson and R. W. Stenzel, p. 535 et seq in Colloid Chemistry Vol VI, Ed. by Jerome Alexander, Rheinhold Publishing Corp., New York (1946) and "Interfacial Films Affecting the Stability of Petroleum Emulsions" by Chas. M. Blair, Jr. in Chemistry and Industry (London), p. 538 et seq (1960).
Early demulsifiers used to resolve petroleum emulsions were water-soluble soaps, Twitchell reagents, and sulfonated glycerides. These products were readily compounded with water to form easily pumpable liquids and were conveniently applied by pumping into flow lines at the well head or by washing down the casing annulus with water to commingle with well fluids prior to their flow to the surface. These products, however, were effective only at relatively high concentrations and their use added substantially to the cost of production.
Some time ago, it was discovered that certain lightly sulfonated oils, acetylated castor oils and various polyesters, all of which were insoluble in water but soluble in alcohols and aromatic hydrocarbons, were much more effective in breaking emulsions. Accordingly, essentially all commercial demulsifier development has led to production of agents which are insoluble in both water and petroleum oils and have other properties to be described below which cause them to spread at oil-water interfaces to form very thin, mobile films which displace any emulsifying agent present in the oil to allow coalescence of dispersed water droplets. Generally, such interfacially active compounds are hereafter referred to as Thin Film Spreading Agents, or "TFSA's". In the past, these have had to be compounded with and dissolved in alcohols or highly aromatic hydrocarbon solvents in order to produce readily applied liquid compositions. A wide variety of such compositions are required to treat the many different emulsions encountered throughout the world.
While present TFSA compositions are highly effective, being, perhaps, up to fifty to a hundred times more effective per unit volume than the original water-soluble demulsifiers, they suffer serious practical deficiencies because of their solubility characteristics. For example, alcohols and the aromatic hydrocarbons, which are required for preparation of liquid, pumpable compositions, are quite expensive, today approaching in cost that of the active demulsifier ingredient itself. Further, such solvents are flammable and thus create safety problems and entail more expense in shipping, storing and use. The low flash point flammability can be improved by using high boiling aromatic solvents, but these are increasingly rare, expensive and dangerous from the standpoint of carcinogenicity and dermatological effects.
Still further, present demulsifiers cannot generally be used in a subterranean oil or gas well, injection well, or the like, since they cannot be washed down with either water (or brine) or a portion of the produced oil, and, being viscous liquids which are required in very small amounts, they cannot be reliably and continuously delivered several thousand feet down at the fluid level in a typical well without use of elaborate and expensive delivery means.
Other applications of TFSA compositions would be facilitated if they were readily soluble or dispersible in water. For example, much heavy, viscous oil is produced in the United States by steam injection procedures. Typically, wet steam is injected into the oil producing strata for several weeks in order to heat the oil, lower its viscosity and increase reservoir energy. Steam injection is then stopped and oil is flowed or pumped from the bore hole which was used for steam injection. Much of the water resulting from condensation of the steam is also produced with the oil in emulsified form. Since emulsions are more viscous than the external phase at the same temperature, and thus create increased resistance to flow, productivity of the steamed wells can be improved by injecting a water-soluble demulsifier into the wet steam during the steam injection period to prevent emulsion formation. See, for example, U.S. Pat. No. 3,396,792, dated Apr. 1, 1966, to F. D. Muggee. At present, the requirement of water solubility seriously limits the choice of demulsifiers for use in steam or water injection to the relatively inefficient compositions.
As disclosed in my co-pending applications, Ser. No. 045,479, filed June 4, 1979 and entitled "Method Of Recovering Petroleum From A Subterranean Reservoir Incorporating A Polyether Polyol", Ser. No. 45,478, filed June 4, 1979, now U.S. Pat. No. 4,260,019, and entitled "Method of Recovering Petroleum From A Subterranean Reservoir Incorporating Resinous Polyalkylene Oxide Adducts", Ser. No. 45,360, filed June 4, 1979, now U.S. Pat. No. 4,216,828, and entitled "Method Of Recovering Petroleum From A Subterranean Reservoir Incorporating An Acylated Polyether Polyol", and Ser. No. 45,470, filed June 4, 1979, and entitled "Method of Recovering Petroleum From A Subterranean Reservoir Incorporating Polyepoxide Condensates Of Resinous Polyalkylene Oxide Adducts And Polyether Polyols", TFSA's are useful in processes for enhanced recovery of petroleum. Used in such processes involving displacement of residual oil by aqueous solutions, polymer solutions and other aqueous systems, these agents act to increase the amount of oil recovered. Such action possibly arises from their ability to further water wetting of reservoir rock, lessen the viscosity of the oil-water interfacial layer and promote coalescence of dispersed droplets of either water or oil in the other phase.
By use of the present aqueous micellar solutions, the introduction of TFSA into aqueous displacement or flooding fluids is greatly facilitated. In addition, the present micellar solutions, per se, or in combination with other components, can be used as the flooding agent or as a pretreating bank or slug ahead of other aqueous fluids.
Other applications for the present TFSA micellar solutions include their use as flocculation aids for finely ground hematite and magnetite ores during the desliming step of ore beneficiation, as additives for improving the oil removal and detergent action of cleaning compositions and detergents designed for use on polar materials, for the improvement of solvent extraction processes such as those used in extraction of antibiotic products from aqueous fermentation broths with organic solvents, for the improvement of efficiency and phase separation in the purification and concentration of metals by solvent extraction with organic solutions of metal complex-forming agents, and as assistants to improve the wetting and dying of natural and synthetic fibers and for other processes normally involving the interface between surfaces of differing polarity or wetting characteristics.